1. Field of the Invention
The present invention relates to an inductive heating furnace for billets having rectangular cross-section, so-called slabs, comprising roller pairs for feeding billets between several pairs of inductive heaters, and more particularly to modules for heating such billets.
2. Prior Art
A common drawback with heaters of the kind specified is that they require a mechanically complicated manipulating device for feeding billets in and out between the respective inductive heater coils. The capacitor bank for power factor correction is large and costly, partly because of the need for a high frequency, and partly because the induction coils have to be dimensioned for the largest billet, even if such sized billets do not constitute main production. Since a high frequency must be used to obtain a reasonable efficiency, the plant has required expensive static frequency convertors. One reason for using a high frequency has been the need to use a low penetration depth for the field generated by the heaters because of the location thereof and the shape of the billets.